1. Field of the Invention
The present invention relates to electro luminescence (EL) devices and electrophotographic printing systems using the same. More particularly, it relates to EL devices having an electrode arrangement including a small number of driving electrodes.
2. Description of the Related Art
EL devices are extensively used as light sources for a variety of apparatuses. The EL device includes at least one row of X direction electrode(s) and a plurality of Y direction electrodes intersecting the X electrode(s). When the capacity of light emitting elements defined by the X direction electrode(s) and the Y direction electrodes in the EL device is increased, the number of electrodes is proportionally increased. Large-scale EL devices of the prior art, however, suffer from the disadvantage that the number of circuit elements for driving the electrodes becomes large, and accordingly, high production costs become inevitable, and the speed at which all of the electrodes can be driven is lowered.
Japanese Unexamined Patent Publication (JPP) No. 59-214672, entitled "an electrophotographic printer", Ishitobi, et al. published on Dec. 4, 1984, discloses the use of an EL panel for an electrophotographic printer. The EL panel is used as a light source instead of a laser optical system or a light emitting diode (LED) array. Electrophotographic printers which use EL panels generally provide the merits of low manufacturing cost, reduced size of the printer, and high quality print outs. JPP No. 59-314672, however, discloses only the use of EL panels of the prior art type, as set forth above, and the principle of the light emitting operation of the EL panel.
EL panels used for electrophotographic printers must be provided with an array containing a large number of EL elements, for example, 1024 or 2048. Accordingly, the electrophotographic printer disclosed in JPP No. 59-214672 suffers from the same disadvantages as set forth above regarding EL devices generally.
In addition, as compared with laser optical and LED array systems, EL panels have an inherent disadvantage of a low light intensity. For example, the light intensity of an EL element is approximately one-hundreth (1/100) of that of one LED. This means that the exposure needed to form a latent image on a light sensitive medium in the electrophotographic printer is insufficient.